Glypican-3 (GPC3) is one of a heparan sulfate proteoglycan family existing on the surface of cells, and it is suggested that GPC3 may participate in cell division in development and in growth of cancer cells, but its function is not as yet well clarified.
It has been found that a certain antibody binding to GPC3 has a cell growth-inhibiting effect through its ADCC (antibody-dependent cytotoxicity) activity and CDC (complement-dependent cytotoxicity) (WO2003/000883, hereby incorporated by reference in its entirety).
In the case where an anticancer agent utilizing the cytotoxicity activity of an antibody is developed, it is desirable that the antibody to be used has enhanced ADCC activity. Thus, an anti-GPC3 antibody having enhanced cytotoxicity activity is desired for the GPC3-recognizing antibody.
An object of the invention is to provide an anti-GPC3 antibody having enhanced cytotoxicity as compared with conventional antibodies.